Wave guide repeater



Dec. 28, 1948. v A. E. BOWEN 2,457,524

l Y WAVE GUIDE REPEATER I Filed May 26, 1945 f l r 5 l 5 5 n n 1 i i 5 nl r a 5 l l.

/N VEN TOR ATTORNEY A. E BOWEN Patented Dec. 28, 1,948j

UNITED STATES PATENT OFFICE WAVE GUIDE REPEATER Application May 26,1945, Serial No. 595,911

'7 Claims.

This invention relates to amplifiers, oscillators,

repeaters and the like and more particularly to a microwave repeaterincorporated in a wave guide of the hollow pipe type.

The arrangement of the invention is particut larly adapted toreenforcing, amplifying or repeating a microwave in a continuous lengthof hollow pipe wave guide, the wave to be amplified serving at one ormore points along the axis of the wave guide to control the action of agroup -or cloud of electrically charged moving particles, such aselectrons. The action of the wave to be amplified upon the particles ispreferably to sort the particles into groups, one group comprisingparticles vibrating in such phase as to transfer a net increment ofenergy from their energy of kinetic motion to the energy of theelectromagnetic wave, thereby intensifying or amplifying the wave.Adjacent to the region in which the sorting of particles occurs, thereis provided a passageway for particles to be transferred to anotherportion of the wave guide. A second group of particles resulting fromthe sorting comprises particles operating in such phase as to absorbenergy from the electromagnetic wave, thereby increasing theirvelocities. The particles which have their velocity thus increased arepreferably directed through the said passageway to the other` portion ofthe wave guide. In this section of the wave guide, provision is made tomake the par-` ticles oscillate substantially in a group by means oflocally applied energy not derived from the wave to be arnplied. Thephase of the Wave in this second section of the wave guide is preferablysuch that the oscillating group of particles will transfer kineticenergy to the electromagnetic wave. Provision is made, in known manner,for a continual supply of fresh particles in the rst section of the waveguide and for the removal of spent particles from either section.

In accordance with the invention, a continuous length of hollow pipewave guide is arranged to have at least two portions which are laterallycontiguous, being separated at one point by a common wall. The laterallycontiguous portions are connected not only axially along the interior ofthe wave guide but laterally as through an aperture in the common wall.A source of charged particles such as a cathode is arranged directlyacross from the aperture in a portion of the wall of the wave guideopposite the aperture and means are provided in each of the laterallycontiguous portions of the wave guide to accelerate electrons from aplurality of directions towards an equilibrium region preferably locatedsubstantially mid-way between a pair of opposite wall portions of thewave guide. ing means is preferably adjusted to produce oscillationshaving substantially the same frequency as the electromagnetic wave tobe amplified. The particles supplied by the cathode are set intooscillation by the acceleratingmeans in the portion of the wave guideincluding the cathode. l'n this portion of the wave guide, theparticles, which may be oscillating in all possible phases at random,are sorted by means of the electromagnetic wave into two groups as abovedescribed, one group returning oscillatory energy to the wave in thesam-e portion of the wave guide, the other group being acceleratedthrough the aperture into the laterally contiguous' portion of the waveguide. This latter group is set into oscillation by the acceleratingmeans in the second portion of the waveguide and delivers a substantialportion of this energy to the electromagnetic wave in that section.

In a preferred embodiment of the invention, the wave guide has fourlaterally contiguous portions separated by three and only three commonwalls in the region of continuity. The inner two laterally contiguousportions are consecutively connected along the length of the Wave guideand the outer two portions are similarly consecutively connected. Thecathode is located effectively in the middle one of the three commonwalls and has active surfaces exposed toward the inner two laterallycontiguous portions. Oscillating clouds of charged particles are formedon either side of the cathode and accelerating means are provided in allfour of the laterally contiguous portions. In this embodiment theelectromagnetic wave may perform the sorting function in two of thelaterally contiguous portions and may absorb energy from the oscillatingparticles in at least two places.

In the drawing, Fig. l is a perspective View, partly in sections, of apreferred embodiment of the invention and Fig. 2 is a wiring scheme anddiagrammatic representation useful in describing the operation of thearrangement shown in Fig. 1,

Referring to Fig. l, a continuous length of wave guide II) of the hollowpipe type is shown arranged in a bent or folded configuration producingfour laterally contiguous portions II, I2, I3 and I4, respectively,which are consecutively connected along the length of the Wave guide inthe order named. The laterally contiguous portions are preferablyarranged with their longi- The accelerattudi'nal axes parallel to eachother, at least in the region of contiguity. In this arrangement, thereare three common walls I5, I6 and I'I, respectively, separating th-epairs of immediately adjacent contiguous portions.

For simplicity, it will be assumed that the wave guide is used totransmit the H11 type of wave, the guide -being of rectangular:cross-section and of suitable dimensions to support a wave of thedesired frequency. This being the case, the electric vector, in thehorizontal portions of the wave guide Ill will lie in the verticaldirection.

The common walls l5, IIS and I'l are preferably provided with transverseslots I8, t9 and 20,. respectively, and these are 'preferably-aligned.in a vertical plane as illustrated.

4 electric field in the neighborhood of each slot. In the embodimentillustrated, the axial separations along the wave guide beginning at thediaphragm 2t are, noted by legends in Fig. 2, va quarter wavelength fromthe diaphragm 26 to the slot I9, one whole wavelength from the slot I9in the wave guide portion II to the opposite side of the-slot I Qfin theportion t2-a half wavelength between the slots I9 'and .'20, twowavelengths from the slot to the slot I3 and a quarter Wavelength fromthe slot I8 to the diaphragm 21. It will be understood that onaccount'of the fold- Jing'of 'the wave guide and other possible disturb-:ing factors, themeasurement given may not in 15r In -the middle` slotIS is preferably mounted a thermionic :cath-Y ode 2i which may be in theform of a rod coatedl with a suitably emissive substance and introducedthrough the side wall of the wave guide I0 through an insulating bushing22 at ,either end. vA heatingcurrent may be set up in the rod 2| throughprojecting end portions such as 23 at either end of the rod. The cathode2l preferably presents a thermionicallyactive surface toward each of thewave guide portions II and I2. anode rods 2li may be provided and theremay be, for example, two of the rods in each portion of the wave guideasshown in Fig.- l, symmetrically arranged in pairs with respect to theplane of the slots I8, I9 and 2,0. The rods 2li preferably are mountedmid-way between the top and bottom walls of the wave guide, as viewed inthe drawing and parallel in direction with the cathode 2|. Each rod 24may be inserted through an insulating bushing 25 in the side wall of thewave guide. The rods preferably are kept out of direct line with theslots I8, I9 and ZII. .l

Diaphragms 26 and 2'! are preferably provided as shown, to define .aresonator therebetween wherein a standing wave pattern of the desiredfrequency may be established. ,Apertures or windows 28 and 29 may beprovided in the respective diaphragms 26 and 21 for input and outputcoupling between the resonator and the remainder of the continuouslength of wave guide I0. The apertures may be sealed with a suitabledielectric material such as glass.

The View in Fig. 1 comprises a longitudinal section of the wave guide I0with the front lhalf cut away.v The walls of the wave guide -Iil arepreferablyhighly conductive, at least over their inner surfaces. Theinterior space of the resonator, at least in the region including thecathode, the slots I8, I9 and 2li, and the anode blocks'24 is preferablyevacuated. To maintain a seal for the vacuum chamber the walls of thewave guide `lll should be vacuum tight, including the bushings 22 and 25and the coupling apertures or windows 28 and 29.

Fig. 2 shows suitable electrical connections to the cathode and anode,the conductive mass of the wave guide III being preferably connected toground. Heating current may be supplied to the cathode 2| by means ofbalanced batteries v3l! and 3|. Anode potential may be applied totherods 24 as by means of a battery 32.

To develop maximum alternating potentialsin the wave guide at theoperating. frequency, the slots I8, I9 and 20 are preferably spaced fromeach other and from the diaphragme` 26 and 21 by appropriate multiplesofa quarter wavelength. The spacing between the slots I8, 'I9 and 2B isalso preferably related to the Wavelength in such manner as to Adevelop.the desiredpolarity inthe.'

A plurality of.

every case Vcor-respond exactly to the linear measurement of the waveguide along the median plane of, the guide, but the exact spacing maybest be determined'by experiment.

. :In the operation of the embodiment illustrated in the drawing, a waveto be amplied and having the frequency of the resonator, -is .introducedthrough the dielecftricwindow .-28 in thediaphragm 26 linto section II-of Vthe resonator. EIhe wave builds up a standing wave pattern intheresonator with polarities at theslots I8, .I9 .and '20 determined by thespacings above described. .The

polari'ties` at a .given instant vare indicated @by arrows fil, 212, I3and dll in Fig. 2. rAt the given instant the arrows Il andlll aredirected away from thev cathode 2i as are also the arrows "d'3, and S46.

arrows di, '42, 'IIS and M would have to be shown Half a cycle earlieror later, yall the with their directions reversed, all 'pointing towardsthe cathode 2l.

Electrons .emerging from the cathode "Z'I `are caused to oscillate aboutthe'median plane of the waveguide dueto the attraction of the anoderodserated thereby and will eventually'be collected'by Electrons which the'anodes 2d in the section I I.

a-re insuch phase as to absorb energy lfrom the standing waves rareaccelerated and may be'hurletl through aperture I8 into the section III.The polarity of the standing 4wave in :section Ill is such as to absorbenergy from those electrons which varrive from lsection 'I I. Such'electrons are *eventually collected by one of the anodes *24 in sectionvI d. Illustrative `trajectories for the two classes/of electronsdescribed are lshown at '5'I and M52, respectively. A corresponding'sorting 'of the electrons wemerging 'from the underside yof vthecathodeas illustrated in the draw-ing, takes place inv wavelguidelsection l2 where one group o'f electrons delivers energy vto thestanding wave in section I2 and the other groups is hurled into sectionI@ and delivers energy to the standing wave there. The number ofelectrons vdriven vthrough the aperturesmay be adjusted to beproportional to fthe intensity ofthe wave 'impressed upon the input,V byappropriate selection of operating potentials.

AWhile the kenergy yexchange between the electrons and the stand-ingwave .in .sections I..I` :and 12011 the one hand may be very nearlybalanced so that there is no material net change in the energy of thestanding wave in either section, on

the other hand, due to the sorting action, the,

energy transfer in sections I3 and I4is evidently quite unbalanced infavor of transfer of energy from the electrons to the wave. The netresult is that the standing wave energy is enhanced at the expense ofenergy supplied to the electrons by the local source, in this case thebattery 32. A portion oi the standing wave energy is delivered throughthe aperture or window 29 in the diaphragm 2l to provide an output whichmay be utilized as desired.

It will be evident that the arrangement as described may be employed asan amplifier or repeater for waves introduced at the input andtransmitted from the output of the system. If desired the input andoutput may be coupled together to provide either regenerativeordegenerative amplication or to form a self-oscillatory system.

The polarity shown by the arrows 4I and 44, indicating that the electricintensity of the standing wave is in the same direction wth respect tothe cathode in sections II and I4, respectively, represents what isusually the. proper relation of polarities at the two slots i8 and I9 topromote absorption of energy by the standing wave at the expense of thekinetic energy of the electrons. Those eiectrons which spendsubstantially a half cycle in traversing the Wave guide section Il,meanwhile absorbing energy from the standing wave, arrive in section I4just as the polarity of the standing wave is reversing and hence theseelectrons will traverse the section I4 in phase opposition to thestanding wave so as to give up energy to the wave. Since many of theelectrons will give up energy during part of a transit and absorb energyduring the remainder or vice versa, the net result may be slightlydifferent from what would be expected from consideration of only suchelectrons as are continually accelerated or continually decelerated. Itmay be advantageous, therefore, to vary the position of the diaphragms.26, 2l, somewhat until a position is found which results in a maximumnet transfer of energy as desired. For this purpose the diaphragms 2Band 2 may be made movable. Precaution should then be taken to preservethe vacuum in the operating space traversed by the electrons.

The addition or subtraction of a whole wavelength, where physicallypossible, in the spacing between two slots, or between a slot and one ofthe diaphragnis will not in general have any rst order eifect upon theoperation of the device.

It will be noted that, due to the folding or turn ing over of the waveguide between portions |`2 and I3, an odd number of half wavelengths isneeded between slots I9 and 20 to bring about the phase relation shownby the arrows 42 and 3. Similarly, an odd number of half wavelengths isneeded between slots I8 and I9 to bring about the phase relation shownby the arrows 4I and All. The use of both sides of the cathode 2lintroduces the additional requirements of an integral number ofwavelengths between the two sides of the cathode. If desired, the slotI9 may be omitted and separate oathodes may be supplied opposite therespective slots I8 and 20, in which case an odd number of halfwavelengths will be needed between either slot I8 or I9 and itsrespective cathode and no limitation need be placed upon the spacingbetween the cathodes.

Where separate cathodes are provided they aret not limited to two innumber. The provision of `resonance and the accompanying appearance of astanding wave pattern is not essential, and the diaphragms 26 and 2"!may be omitted, in which case a traveling `wave may be impressed at theinput and the wave will appear at the output intensified. In this casethe spacings between the cathode positions and the slots will need to beadjusted as before, and when so adjusted, the electric intensities inthe wave guide portions connected by a given slot will have the correctphase relationship at all times.

What is claimed is:

l. A continuous length of hollow pipe wave guide having two laterallycontiguous portions separated by a common wall having an aperture, acathode directly across from said aperture in a portion of the wallofthe wave guide opposite saidy common wall, and means in each ofsaidlaterally `contiguous portions of the wave guide to impartreciprocating motion to charged particles from said cathodein therespective portion of the wave guide.

2. A continuous length of hollow pipe wave guide having two laterallycontiguous portions separated by a common wall having an' aperture, acathode directly across from said aperture in a portion of the wall ofthe wave guide opposite said common wall, each of said laterallycontiguous portions of the wave guide to accelerate electrons from aplurality of directions toward a region substantially midway between apair of opposite walls in the respective portion of the wave guide.

3. A continuous length of hollow pipe wave guide having two laterallycontiguous portions spaced an integral number of half wavelengths apartwith respect to transmission of waves through the said wave guide at apreassigned operating frequency and separated laterally in the region ofcontiguity by a common wall having an aperture, a cathode directlyacross from said aperture in a portion of the wall of the wave guideopposite said common wall, and means in each of said laterallycontiguous portions of the wave guide to accelerate electrons from aplurality of directions toward a region substantially midway between apair of opposite walls in the respective portion of the wave guide.

4. A continuous length of hollow pipe wave guide folded upon itself toform two laterally contiguous portions spaced an odd number of halfwavelengths apart with respect to transmission of waves through the saidwave guide at a preassigned operating frequency and separated laterallyby a common wall having an aperture, a cathode directly across from said-aperture in a. portion of the wall of the wave guide opposite saidcommon wall, and means in each of said laterally contiguous portions toaccelerate electrons v yfrom a plurality of directions toward a regionsubstantially midway between a pair of opposite walls in the respectiveportion of the wave guide.

5. A continuous length of hollow pipe wave guide having four laterallycontiguous portions mounted with their longitudinal axes parallel toea-ch other in the region of contiguity and having three and only threecommon walls separating one laterally contiguous portion from the next,the inner two laterally contiguous portions being consecutivelyconnected along the length of the guide, and the outer two portionsbeing similarly consecutively connected, a cathode lo andnon-alternating means in"y atea-eea;

cated in the middle one of said three common walls and having activesurfaces exposed tov the laterally contiguous wave guide portions oneither side of said middle wall, said common walls containing a total oftwo apertures, one in each com-V mon wall portion opposite one of therespective active cathode surface, and means in each or" .said fourlaterally contiguous portions of .the

wave guide to accelerate electrons from va plurality of directionstoward an Aequilibrium region located substantially midway between VoneVof said apertures and the opposite wall of the wave guide.

6. A continuous length of hollow pipe wave guide having four laterallycontiguous portions mounted parallel to each y other and having-threeand only three common walls separating one laterally contiguous portionfrom the next, a cathr ode located in the middle one of saidthreecommonwalls and having active surfaces exposed to the laterallycontiguous wave guide portions;

7. A'continuous hollow pipe type of wave guide" having fourflaterallylcontiguousportions mounted parallel to each other and having only vthreecommon walls separating one' laterally Acontiguous portion-from thenext,` a .cathode locatedlin the middle one of said three common wallsand having active surfaces exposed to the laterally contiguous waveguide portions on either siderof. said middle common wall', said commonwalls containing a total of two apertures, one in each,

common wall portion opposite one of 'said active cathode surfaces, aplurality of pairs of anodes,l

one pair in each of said laterally contiguous Wave guide portions, theanodes of each pair being symmetrically disposed with respect totheWalls of. the Wave guide and with respect to a plane passing1 through alpoint on the cathode surface and one of said apertures, and meansconnected to saidA anodes to maintain the saidanodes at a positivepotential with respect to thewallsof th wave guide. f i

, ARNOLD E. BOWEN.

REFERENCES' orrED The following references are of recordinthe of thispatent:

UNITED STATES lPATENTS 1\lunfrloer Name Date :lo 2,153,728 SouthworthApr. 11, 1939' 2,368,031 Y Llewellyn Jan. 23,1945

